妙法蓮華經文句 9.66

9.66

復次，寂場本迹復有多種，或以涅槃為本，從真起應為迹，迹本俱空言思雙斷，故不思議一也。或以俗為本，從俗起應為迹，迹本深廣，下地不能言思邊涯，故言不可思議一也。或以中為本，從中起應為迹，迹本皆言語道斷心行處滅，故云不思議一也。

Furthermore, the origin and traces at the site of quiescence have multiple kinds: sometimes taking nirvāṇa as the origin and giving rise to the response from the real as the traces, where traces and origin are both empty and speech and thought are both severed, therefore they are an inconceivable one. Sometimes taking the conventional as the origin and giving rise to the response from the conventional as the traces, where traces and origin are deep and vast, so that lower stages cannot speak or think of their boundaries, therefore it is called an inconceivable one. Sometimes taking the middle as the origin and giving rise to the response from the middle as the traces, where traces and origin are both such that the path of speech is severed and the realm of mental activity extinguished, therefore it is called an inconceivable one.